package nowcoder.hw.hj10;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader =new BufferedReader(new InputStreamReader(System.in));
        String str= bufferedReader.readLine();
        HashSet<Object> set = new HashSet<>();
        char[] chars = str.toCharArray();
        for (int i=0;i<str.length();i++){
            set.add(chars[i]);
        }
        System.out.println(set.size());
    }
}
